This invention relates to a light-sensitive silver halide color photographic material. Particularly, it relates to a light-sensitive color photographic material having broad exposure latitude, excellent in gradation and graininess and also good in desilverization performance during processing.
Light-sensitive material (abbreviated for light-sensitive silver halide color photographic material, hereinafter the same), when this is subjected to imagewise exposure, is required to form an imagewise image with an appropriate degree of shade of the negative of the light-sensitive material corresponding to lightness and darkness of the object to be photographed, even when there may be excess or shortage of exposure. Light-sensitive material with broad latitude to cope with such excess or shortage of exposure have been strongly demanded. Practically, however, increased exposure will result in poor graininess and sharpness, and this poses a general problem in light-sensitive materials.
For example, in order to obtain a light-sensitive material with broad exposure latitude, it has been proposed in the prior art to constitute a light-sensitive material by use of a silver halide emulsion with broad grain size distribution, or to constitute a light-sensitive material by use of a silver iodobromide emulsion having a high iodide content, or to reduce the silver quantity of the silver halide in the silver halide emulsion to be used for the light-sensitive material. However, according to any of these techniques, graininess is deteriorated greatly, and there also remains the problem of lowering in sensitivity of the light-sensitive material.
There is also provided a technique which attempts to broaden exposure latitude of the light-sensitive material without deterioration of graininess. For example, there is disclosed the method in which the light-sensitive material is constituted by use of a mixture of several kinds of silver halide emulsions with different mean grain sizes, but the improved effect of exposure latitude was not satisfactory.
Further, another technique is also disclosed, in which the above silver halide emulsions are emulsions comprising silver halide grains having mono-dispersibility, and the light-sensitive material is constituted by use of a mixture of several kinds of these emulsions. For example, Japanese Unexamined Patent Publication No. 78831/1981 has accomplished broadened exposure latitude by use of several kinds of silver halide emulsions having substantially the same grain sizes with different iodide contents in the surface layer of the mono-dispersed silver halide grains. However, according to this method, the improved effect of graininess was not satisfactorily great.
On the other hand, in negative light-sensitive materials, disclosures has been made about the method in which color formed density of the image is lowered by use of a non-diffusible compound capable of releasing a diffusive development inhibiting compound through the reaction with the oxidized product of a developing agent (DIR compound) or about the method in which the color formed density of the image is similarly lowered by use of a coupler having multi-equivalence. In these techniques, more silver halide is necessary for compensating the gradation of the light-sensitive material, which is very disadvantageous in aspect of conservation of resources and cost, and further in aspect of deterioration of desilverization performance during processing.
However, in order to satisfy the performances particularly demanded for the color light-sensitive materials in recent years, namely the requirements of higher image quality and higher sensitivity, in spite of the disadvantages as mentioned above, the amount of silver halide used tends to be increased, and it has been desired to have a technique which improves latitude of exposure and graininess, and further a technique to improve desilverization performance.